Bone growth stimulator

ABSTRACT

A bone growth stimulator is provided. In one embodiment, the device has an elliptically shaped transducer coil. The coil provides increased therapeutic benefit to a wearer. An elliptically shaped housing supports and contains the coil. The housing includes a curvature when viewed in profile, such that a first surface of the housing is convex. The convex surface is adapted to be positioned against a wearer&#39;s lower back, to nest within the natural curvature thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.unknown, titled: BONE GROWTH STIMULATOR, filed on Jul. 14, 2005, theentire contents of which are hereby expressly incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to devices for stimulating the growth ofbone cells.

2. Description of the Related Art

Magnetic field therapy is often used to treat a variety of medicalconditions. For example, the following U.S. patents teach variousdevices and methods of applying magnetic fields to treatment sites: U.S.Pat. No. 4,818,697 to Liboff et al., issued Apr. 4, 1989, titled“Techniques for Enhancing the Permeability of Ions Through Membranes;”U.S. Pat. No. 4,932,951 to Liboff et al., issued Jun. 12, 1990, titled“Method and Apparatus for Controlling Tissue Growth and an AppliedFluctuating Magnetic Field;” U.S. Pat. No. 5,059,298 to Liboff, issuedOct. 22, 1991, titled “Method and Apparatus for Regulating TransmembraneIon Movement;” U.S. Pat. No. 5,195,940 to Baylink, issued Mar. 23, 1993,titled “Method for Increased Production of Growth Factor in LivingTissue Using an Applied Fluctuating Magnetic Field;” U.S. Pat. No.5,330,410 to Baylink, issued Jul. 19, 1994, titled “Method for IncreasedProduction of Growth Factor in Living Tissue Using an AppliedFluctuating Magnetic Field;” and U.S. Pat. No. 5,792,040 to Koeneman etal., issued Aug. 11, 1998, titled “Patient Interface Device forGenerating Therapeutic Magnetic Fields.” Each of the above-listedpatents is assigned to the assignee of the present application, and eachis incorporated herein by reference in its entirety.

To apply a magnetic field to a treatment site, various wearer interfacedevices have been designed that place one or more magnetic fieldgenerating coils adjacent a body region that is to be treated. U.S. Pat.No. 5,139,474, entitled, “Medical Treatment Device with Self-CenteringSecuring Members,” illustrates one example of such a wearer interfacedevice. The apparatus described therein engages a region of a wearer'sbody, such as a limb, with a pair of coils in opposed relation relativeto the treatment region. This prior art apparatus has a relatively rigidshell comprising two rigid shell halves that are hinged together at asingle hinge axis. The two shell halves pivot away from each other to anon-treating position and pivot towards each other in a treatmentposition. Means are provided for securing the shell halves together inthe treatment position. One coil is disposed in each shell half and thepair of coils are used to generate the therapeutic magnetic field. Thatis, a voltage of a given amplitude and frequency is applied to the coilsto induce a current and produce a magnetic field. Resilient securingmembers extend inward from the shell halves and have a flexible backingthat applies a force radially from the shell halves. The resilientsecuring members deform outward to conform to the anatomy of the regionto which it is applied.

U.S. Pat. No. 4,616,629, entitled “Coil Construction for ElectromagneticTreatment of an Afflicted Body Region,” describes a single-coil wearerinterface device defining two U-shaped cavities. The two cavities are ofunequal size, which permits the device to fit two different sizes ofanatomical structures. Canadian Patent No. 1,314,941 discloses atreatment coil that is generally circular, having outwardly spiralingmultiple strands of conductors.

SUMMARY OF THE INVENTION

The preferred embodiments of the present bone growth stimulator haveseveral features, no single one of which is solely responsible for theirdesirable attributes. Without limiting the scope of this bone growthstimulator as expressed by the claims that follow, its more prominentfeatures will now be discussed briefly. After considering thisdiscussion, and particularly after reading the section entitled“Detailed Description of the Preferred Embodiments,” one will understandhow the features of the preferred embodiments provide advantages, whichinclude increased therapeutic benefit, and an ergonomic design that iscomfortable for wear against the wearer's lower back.

One embodiment of the present bone growth stimulator comprises atransducer coil adapted to receive a voltage input and generate amagnetic field output, and a housing adapted to support and contain thetransducer coil. The housing includes a curvature when viewed inprofile, such that a first side of the housing is convex.

Another embodiment of the present bone growth stimulator comprises atransducer coil adapted to receive a voltage input and generate amagnetic field output, and a housing adapted to support and contain thetransducer coil. The housing has an elliptical shape, and is adapted tobe positioned against a wearer's lower back such that a major axis and aminor axis of the elliptical housing are substantially perpendicular tothe anterior/posterior axis.

Another embodiment of the present bone growth stimulator comprises amethod of stimulating bone growth. The method comprises the steps ofpositioning a transducer coil in the lumbar region of a wearer's back,and applying a voltage across the coil to produce a magnetic fieldaround the coil. The coil has an elliptical shape, and is positionedagainst the wearer's back such that a major axis and a minor axis of theelliptical coil are substantially perpendicular to the wearer'santerior/posterior axis.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present bone growth stimulator,illustrating its features, will now be discussed in detail. Theseembodiments depict the novel and non-obvious bone growth stimulatorshown in the accompanying drawings, which are for illustrative purposesonly. These drawings include the following figures, in which likenumerals indicate like parts:

FIG. 1 is a front perspective view of a preferred embodiment of thepresent bone growth stimulator;

FIG. 2 is a right-side elevational view of the bone growth stimulator ofFIG. 1 secured to a wearer's lower back;

FIG. 3 is a front elevational view of the housing for the transducercoil of the bone growth stimulator of FIG. 1;

FIG. 4 is a rear elevational view of the housing for the transducer coilof the bone growth stimulator of FIG. 1;

FIG. 5 is a rear elevational view of the bone growth stimulator of FIG.1; and

FIG. 6 is a rear elevational view of the housing for the transducer coilof the bone growth stimulator of FIG. 1, illustrating a rear cover ofthe housing removed to expose the coil.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a preferred embodiment of the present bone growthstimulator 10. The device 10 may be used, for example, as an adjunct tospinal fusion, or in other applications where it is beneficial tostimulate the growth of bone cells. The device 10 includes a housing 12that contains an electrical transducer coil 14 (FIG. 6). The coil 14comprises a plurality of windings of electrically-conductive wire. Whena voltage is applied across the windings, as described below, the coil14 produces a magnetic field that is useful for stimulating the growthof bone cells. The housing 12 may be placed at the small of the wearer'sback 16, as shown in FIG. 2, so that the wearer's spine is positionedwithin the magnetic field generated by the coil 14. The magnetic fieldstimulates the growth of bone cells within the spine.

With continued reference to FIG. 1, the device 10 further includes acontrol box 18 that communicates with the transducer coil 14 viaelectrical wiring 20. Those of ordinary skill in the art will appreciatethat the device may include a control device that communicates with thetransducer coil remotely, that is, without any electrical wiringextending between the control device and the transducer coil. Thecontrol box 18 preferably contains a power source (not shown), such asbatteries, to power the device 10, and a signal generating printedcircuit board (not shown). The power source generates a voltage, whichis then output to the transducer coil 14. The current traveling throughthe coil 14 generates a magnetic field around the coil 14, in a mannerwell-known in the art.

The printed circuit board creates and controls the electrical output tothe transducer coil 14. A display panel 22 on the control box 18provides information to the user about the operating status of thedevice 10. In the illustrated embodiment, the display panel 22 comprisesan LCD display. The control box 18 further comprises a push button 24for activating and deactivating the device 10. Alternatively, means forcontrolling the device 10 could be integral with the device 10.

FIGS. 3 and 4 illustrate the housing 12 in front and rear elevationalaspect, respectively. In FIG. 3, the housing 12 is illustrated togetherwith a wearer interface pad 26 (see FIG. 5), while in FIG. 4 the pad 26has been removed for clarity. The housing 12 includes an outer ringportion 28 that is shaped substantially as an ellipse. The ellipticalshape of the housing 12 provides support and containment for the coil14, which also preferably has an elliptical shape (FIG. 6). However,those of ordinary skill in the art will appreciate that the housing 12and/or the coil 14 could have a different shape, such as circular.

With reference to FIG. 3, the elliptical housing 12 and coil 14 eachinclude a major axis A_(major) and a minor axis A_(minor). Withreference to FIG. 2, when the housing 12 is positioned in the wearer'slumbar region and the wearer is standing, the major axis A_(major)extends substantially vertically along the wearer's spine and the minoraxis A _(minor) extends substantially horizontally. Those of ordinaryskill in the art will appreciate that the housing 12 could be orienteddifferently when positioned in the wearer's lumbar region. For example,the major axis A_(major) could extend substantially horizontally and theminor axis A _(minor) could extend substantially vertically along thewearer's spine. However, no matter the orientation of the wearer, boththe major axis A_(major) and the minor axis A _(minor) are preferablysubstantially perpendicular to the wearer's anterior/posterior axis whenthe device 10 is positioned adjacent the wearer's lumbar region.

With further reference to FIGS. 3 and 4, the housing 12 includes acentral portion 30 that is shaped substantially as an X. The centralportion 30 braces the outer ring portion 28, increasing the structuralintegrity and durability of the housing 12. The central portion 30 alsoprovides support and containment for additional components of the device10. Those of ordinary skill in the art will appreciate that the centralportion could embody a number of other shapes, such as a three-pointedstar or a five-pointed star.

The housing 12 further includes first and second substantially verticalposts 32 disposed on opposite sides of the central portion 30. Each post32 extends between vertically spaced arms of the X-shaped centralportion 30. The posts 32 are adapted to receive end portions of strapsthat secure the housing 12 to the wearer, as described below.Alternatively, the posts 32 may be eliminated, and the straps may besecured directly to the other portions of the housing 12.

The housing 12 is preferably constructed of a material that is durableand lightweight. In one embodiment, the housing 12 is constructed of aplastic, such as an ABS/PC blend. Those of ordinary skill in the artwill appreciate that other materials, such as metals, could be used toconstruct the housing 12. To reduce manufacturing costs, the housing 12may be injection-molded. In the illustrated embodiment, the housing 12is constructed of two pieces (a front piece 34 and a back piece 36,FIG. 1) that are each formed separately and then secured together. Forexample, the pieces 34, 36 may be secured together with screws 38 (FIG.4) and/or the pieces 34, 36 may include mating tabs and slots (notshown) that allow the pieces 34, 36 to snap together. The mating pieces34, 36 define a hollow interior space that contains several components,as described below.

The central portion 30 of the housing 12 includes an interior space thatcontains electrical circuitry. For example, the circuitry may comprise aprinted circuit board 40 that includes a sensor. The sensor may measurethe output of the device 10 and feed the information back to the mainprinted circuit board (in the control box 18) to control the magneticfield output of the device 10. Electrical wiring 42 extends from theprinted circuit board to the coil 14, and from the printed circuit boardto an input socket 44 that receives a plug 46 (FIG. 1) at one end of thewiring 20 that extends between the control box 18 and the housing 12.

With reference to FIG. 6, the transducer coil 14 preferably extendsaround the periphery of the space inside the outer ring portion 28 ofthe housing 12. The coil 14 thus forms an ellipse when viewed in frontor rear elevational aspect. In this configuration, the coil 14 producesa magnetic field that stimulates the growth of bone cells in thewearer's spine, thus producing a therapeutic benefit for the wearer.

With reference to FIG. 4, in the illustrated embodiment a rear surface48 of the housing 12 includes portions of a hook portion 50 of ahook-and-loop fastener. The hook portions are located along an upper end52 and a lower end 54 of the outer ring portion 28. However, the hookportions 50 could be located in other areas. The hook portions 50 areadapted to receive a wearer interface pad 26, which is illustrated inFIGS. 1-3 and 5. Those of ordinary skill in the art will appreciate thata wearer interface pad could be secured to the housing 12 in anothermanner, such as with snaps, or the pad could wrap entirely around thehousing 12.

In one embodiment, the pad 26 is constructed of a soft, flexiblematerial that is comfortable for wear against the skin. For example, thepad 26 may be constructed of urethane foam. An outer surface of the pad26 preferably includes a loop portion of a hook-and-loop fastener. Inthe urethane foam embodiment, substantially the entire outer surface ofthe pad 26 is covered with loop material. The pad 26 includes aperimeter that is substantially the same size and shape as the outerring portion 28. The pad 26 is thus adapted to be received upon the rearsurface 48 of the housing 12, such that the outer perimeters of the pad26 and housing 12 substantially align. Abutting contact between the hookportions 50 and the loop material on the pad 26 retains the pad 26 uponthe housing 12.

With reference to FIGS. 3 and 5, in the illustrated embodiment, the pad26 includes a plurality of holes 56 in upper and lower regions. Theholes 56 increase the breathability of the device 10 by enabling heatand moisture from the wearer to pass through the pad 26. However, thoseof skill in the art will appreciate that the holes 56 need not beprovided. The pad 26 further includes first and second substantiallyvertical slits 58 that align with the posts 32 on the housing 12. Theslits 58 enable end portions 60 of straps 62 to pass through, so thatthe straps 62 can be secured to the housing 12. An end portion 60 ofeach strap 62 passes through its respective slit 58, around itsrespective post 32, back through the slit 58, and folds over the strap62, as shown in FIG. 5. Each strap 62 preferably includes a depressedportion 64 having a perimeter 66 that matches the perimeter shape of thestrap end portion 60. The strap end portion 60 thus nests within thedepression 64. In one embodiment, the strap end portion 60 includes aportion of a hook portion 68 of a hook-and-loop fastener. The hookportion 68 mates with loop material in the depression 64 to secure thestrap end portion 60 to the strap 62.

As illustrated in FIG. 2, the housing 12 and pad 26 rest against thewearer's lower back when the device 10 is in use. The pad 26 directlyabuts the wearer (although the wearer may wear the device 10 over his orher clothing) and provides a comfortable interface between the housing12 and the wearer's skin. The straps 62 extend around the wearer's waistand join at the wearer's abdomen. In one embodiment, an end of one strap62 includes a hook portion (not shown) of a hook-and-loop fastener, andan end of the other strap 62 includes a loop portion (not shown) of ahook-and-loop fastener. The mating hook-and-loop portions secure thedevice 10 to the wearer. Those of ordinary skill in the art willappreciate that the ends of the straps 62 could include alternativesecuring means, such as a buckle, for example. The straps 62 arepreferably flexible and soft, so as to be comfortable. In oneembodiment, the straps 62 are constructed of the same material as thepad 26.

As FIG. 2 illustrates, the housing 12 includes a curvature so that therear surface 48 of the housing 12 is convex. The rear surface 48 facesthe wearer's lower back when the device 10 is in use. The housing 12 isthus adapted to abut, and nest within, the wearer's lower back, whichincludes a naturally concave curvature when viewed in profile. The pad26, which is preferably constructed of a soft and flexible material,conforms to the space between the housing 12 and the wearer's lowerback. The curvature of the housing 12 creates a wearer interface thatmore closely matches the wearer's anatomy and leads to greater wearercomfort. In the illustrated embodiment, the curvature of the housing 12follows a path that traces an arc of substantially constant radius.However, as those of ordinary skill in the art will appreciate, thecurvature of the housing 12 may follow a path that traces an arc ofvarying radius.

In general, the stronger the magnetic field that can be applied to atreatment area, the greater the therapeutic benefits. Further, themagnetic field generated by a transducer coil has the greatest strengthin the area close to the coil. Thus, the curvature of the housing 12advantageously brings a greater portion of the transducer coil 14 closerto the wearer. As FIG. 2 illustrates, the curvature of the housing 12follows the contour of the wearer's back so that there are no gapsbetween the interface pad 26 and the wearer's skin. Bringing allportions of the coil 14 closer to the wearer brings a stronger portionof the magnetic field closer to the treatment area and createstherapeutic benefits.

SCOPE OF THE INVENTION

The above presents a description of the best mode contemplated forcarrying out the present bone growth stimulator, and of the manner andprocess of making and using it, in such full, clear, concise, and exactterms as to enable any person skilled in the art to which it pertains tomake and use this bone growth stimulator. This bone growth stimulatoris, however, susceptible to modifications and alternate constructionsfrom that discussed above that are fully equivalent. Consequently, thisbone growth stimulator is not limited to the particular embodimentsdisclosed. On the contrary, this bone growth stimulator covers allmodifications and alternate constructions coming within the spirit andscope of the bone growth stimulator as generally expressed by thefollowing claims, which particularly point out and distinctly claim thesubject matter of the bone growth stimulator.

1. A device for stimulating bone growth, comprising: a transducer coilfor generating a magnetic field; and a housing adapted to support andcontain the transducer coil; wherein the housing includes a curvaturewhen viewed in profile, such that a first side of the housing is convex.2. The device for stimulating bone growth of claim 1, wherein a secondside of the housing opposite the first side is concave.
 3. The devicefor stimulating bone growth of claim 1, further comprising a padconstructed of a relatively soft and flexible material, and wherein thepad is configured to be secured to the first side of the housing.
 4. Thedevice for stimulating bone growth of claim 1, wherein the housingincludes an outer ring portion that is shaped substantially as anellipse.
 5. The device for stimulating bone growth of claim 4, whereinthe housing further includes a central portion that extends betweenopposite sides of the outer ring portion.
 6. The device for stimulatingbone growth of claim 5, wherein the central portion resembles an X. 7.The device for stimulating bone growth of claim 1, further comprising atleast one strap configured to secure the housing to a wearer.
 8. Thedevice for stimulating bone growth of claim 1, further comprising acontrol box configured to control the input to and output from thetransducer coil.
 9. The device for stimulating bone growth of claim 1,wherein the housing traces an arc of substantially constant radius. 10.A device for stimulating bone growth, comprising: a transducer coiladapted to generate a magnetic field; and a housing adapted to supportand contain the transducer coil; wherein the housing has an ellipticalshape, and is adapted to be positioned against a wearer's lower backsuch that a major axis and a minor axis of the elliptical housing aresubstantially perpendicular to the anterior/posterior axis of thewearer.
 11. The device for stimulating bone growth of claim 16, furthercomprising a wearer interface pad constructed a relatively soft andflexible material, and wherein the pad is configured to abut a rearsurface of the housing.
 12. The device for stimulating bone growth ofclaim 10, wherein the transducer coil has an elliptical shape.
 13. Thedevice for stimulating bone growth of claim 10, further comprising atleast one strap configured to secure the housing to a wearer.
 14. Amethod of stimulating bone growth, comprising the steps of: positioninga transducer coil in the lumbar region of a wearer's back, wherein thecoil has an elliptical shape, and is positioned against the wearer'sback such that a major axis and a minor axis of the elliptical coil aresubstantially perpendicular to the wearer's anterior/posterior axis; andproducing a magnetic field around the coil.